390 ANDRE CROTTI 



Malignant Thymomata 



Malignant tumors of the thymus may be classified in two large groups: 

 those belonging to the family of sarcomata, and those belonging to the 

 family of carcinomata. The ones most frequently found are the sar- 

 comata ; they take their origin in the connective tissue of the thymus. 

 The lymphoid cells of the cortical substance are capable, too, of giving 

 rise to sarcoma, hence, the name, lymphosarcoma. This is the most com- 

 mon form. 



The pure carcinomata are much more rare, whereas the mixed tumors 

 are more common. The thymic carcinoma occurs in a rather advanced 

 time of life, while the lymphosarcoma occurs in an earlier period. 



The lymphosarcoma was called by Grandhomme, in 1900, thymoma. 

 The coining of the word is a happy one, insofar as it designates the organ 

 involved, but it does not give any information as to the nature of the 

 tumor. Indeed, a thymoma may be benign or it may be malignant. If 

 malignant, it may be sarcomatous, or carcinomatous, or both together. 

 Hence, we ought to say a carcinomatous thymoma, a sarcomatous thy- 

 moma, etc. 



There is great confusion in the nomenclature adopted by the writers, 

 some describing as sarcomata tumors regarded by others as carcinomata, 

 and vice versa. The reason is because there is such great difficulty in 

 dividing sharply every variety, and because the differences between car- 

 cinoma and sarcoma are sometimes very scant. This confusion is due, 

 according to Ambrosini, to the great polymorphism of the thymic cells, 

 of the lymphocytes, of the reticular cells, of the giant, plasma, and eosino- 

 phile cells. Their interrelation produces a histological picture very sim- 

 ilar to the one of Hodgkin's granuloma, hence, according to Ewing, "the 

 great majority of thymic tumors and especially of mixed growths, repre- 

 sent infectious granulomata, or particular forms of cell growths on the 

 basis of the infectious granuloma. This, from the etiological point of 

 view, offers a simpler explanation for the great variety of structural forms 

 which thymic tumors present." 



The sole criterion that one may accept for the diagnosis of tumor of 

 thymic origin is the presence in that tumor of IlassalTs corpuscles. It, 

 however, polyhedral or giant cells are present then the probability of the 

 thymic origin of these tumors becomes more certain, because according to 

 Ertmann, Weigert and Lacquer, these large cells are most likely of reticu- 

 lar origin. 



In surveying the literature of the cases so reported, only a few can 

 be accepted as primary tumor of the thymus. The majority of the cases 

 reported are most probably of thymic origin but not absolutely beyond 

 doubt. 



